The present invention relates to a new and improved method for the continuous casting of multi-strands, wherein metal is teemed, typically steel, from at least one tundish, the strands which are formed are withdrawn from the continuous casting molds with the same speed or velocity, and the bath level or meniscus in the continuous casting molds is maintained at the desired height. The invention furthermore pertains to a new and improved apparatus for the performance of the aforesaid method.
In the case of multi-strand continuous casting installations an individual strand withdrawal unit or assembly is operatively associated usually with each strand, so that the withdrawal unit can be operated at an individual strand withdrawal speed. In order to maintain the spacing between the cast strands small, there are known to the art withdrawal assemblies or units working with hollow withdrawal rolls. Through these hollow withdrawal rolls there are guided drive shafts for neighboring strands. Such withdrawal units permit the realization of a strand withdrawal speed which is accommodated to each strand, but however are extremely complicated in construction and quite expensive.
Furthermore, it is known in this technology to subdivide plate molds of slab casting installations by means of cooled intermediate walls. By virtue of these measures it is possible to simultaneously cast, at a single-slab casting installation, two narrow slabs or three blooms. Here, it is necessary that the tundish be equipped with appropriately arranged pour nozzles at the base thereof, which, in turn, are equipped with closure elements. The strands which are fabricated in such type of continuous casting installation, by virtue of the construction of the strand guide or roller apron arrangement and the withdrawal unit, are withdrawn from the continuous casting mold with the same speed, and, as a general rule, also commonly cut or separated. The bath level or meniscus of the individual strands is manually maintained at its reference height, or with the aid of bath level-regulation devices by means of stopper or slide controlled pouring nozzles. The simultaneous casting of a number of strands from a plate mold is usually referred to in the art as twin or triple-strand casting.
However, twin castings which have been introduced into practise only have been employed for the fabrication of narrow slabs or blooms. Small sectional shapes, such as billets, have not been fabricated up to the present in twin casting arrangements. On the one hand, difficulties prevail with respect to operational safety, in maintaining the bath level at increased casting speeds at the reference height, and, on the other hand, there are required expensive closure and regulation elements for each strand.